What type of malware includes programs that block the user from accessing their data?

Ransomware is a type of malware specifically designed to block users from accessing their data, typically by encrypting the files on their system. The attacker then demands a ransom payment in exchange for the decryption key, which is needed to restore access to the affected data. This method of operation impacts both individuals and organizations, as it can halt operations and lead to significant data loss or financial damage if the victim cannot regain access to their files.

While adware is primarily focused on delivering unwanted advertisements to users, and spyware gathers user information without their consent, neither of these variants directly restricts access to data in the same way ransomware does. Worms, on the other hand, are self-replicating programs that typically spread through networks, but they do not inherently block user access to their data. Thus, ransomware is uniquely characterized by its ability to hold data hostage, making it the correct choice in this scenario.